/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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/*
 * @author Charlton Innovations, Inc.
 */

package java.awt.font;

import java.awt.RenderingHints;

import static java.awt.RenderingHints.*;

import java.awt.geom.AffineTransform;

/**
 * The <code>FontRenderContext</code> class is a container for the
 * information needed to correctly measure text.  The measurement of text
 * can vary because of rules that map outlines to pixels, and rendering
 * hints provided by an application.
 * <p>
 * One such piece of information is a transform that scales
 * typographical points to pixels. (A point is defined to be exactly 1/72
 * of an inch, which is slightly different than
 * the traditional mechanical measurement of a point.)  A character that
 * is rendered at 12pt on a 600dpi device might have a different size
 * than the same character rendered at 12pt on a 72dpi device because of
 * such factors as rounding to pixel boundaries and hints that the font
 * designer may have specified.
 * <p>
 * Anti-aliasing and Fractional-metrics specified by an application can also
 * affect the size of a character because of rounding to pixel
 * boundaries.
 * <p>
 * Typically, instances of <code>FontRenderContext</code> are
 * obtained from a {@link java.awt.Graphics2D Graphics2D} object.  A
 * <code>FontRenderContext</code> which is directly constructed will
 * most likely not represent any actual graphics device, and may lead
 * to unexpected or incorrect results.
 *
 * @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING
 * @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS
 * @see java.awt.Graphics2D#getFontRenderContext()
 * @see java.awt.font.LineMetrics
 */

public class FontRenderContext {

  private transient AffineTransform tx;
  private transient Object aaHintValue;
  private transient Object fmHintValue;
  private transient boolean defaulting;

  /**
   * Constructs a new <code>FontRenderContext</code>
   * object.
   */
  protected FontRenderContext() {
    aaHintValue = VALUE_TEXT_ANTIALIAS_DEFAULT;
    fmHintValue = VALUE_FRACTIONALMETRICS_DEFAULT;
    defaulting = true;
  }

  /**
   * Constructs a <code>FontRenderContext</code> object from an
   * optional {@link AffineTransform} and two <code>boolean</code>
   * values that determine if the newly constructed object has
   * anti-aliasing or fractional metrics.
   * In each case the boolean values <CODE>true</CODE> and <CODE>false</CODE>
   * correspond to the rendering hint values <CODE>ON</CODE> and
   * <CODE>OFF</CODE> respectively.
   * <p>
   * To specify other hint values, use the constructor which
   * specifies the rendering hint values as parameters :
   * {@link #FontRenderContext(AffineTransform, Object, Object)}.
   *
   * @param tx the transform which is used to scale typographical points to pixels in this
   * <code>FontRenderContext</code>.  If null, an identity transform is used.
   * @param isAntiAliased determines if the newly constructed object has anti-aliasing.
   * @param usesFractionalMetrics determines if the newly constructed object has fractional
   * metrics.
   */
  public FontRenderContext(AffineTransform tx,
      boolean isAntiAliased,
      boolean usesFractionalMetrics) {
    if (tx != null && !tx.isIdentity()) {
      this.tx = new AffineTransform(tx);
    }
    if (isAntiAliased) {
      aaHintValue = VALUE_TEXT_ANTIALIAS_ON;
    } else {
      aaHintValue = VALUE_TEXT_ANTIALIAS_OFF;
    }
    if (usesFractionalMetrics) {
      fmHintValue = VALUE_FRACTIONALMETRICS_ON;
    } else {
      fmHintValue = VALUE_FRACTIONALMETRICS_OFF;
    }
  }

  /**
   * Constructs a <code>FontRenderContext</code> object from an
   * optional {@link AffineTransform} and two <code>Object</code>
   * values that determine if the newly constructed object has
   * anti-aliasing or fractional metrics.
   *
   * @param tx the transform which is used to scale typographical points to pixels in this
   * <code>FontRenderContext</code>.  If null, an identity transform is used.
   * @param aaHint - one of the text antialiasing rendering hint values defined in {@link
   * java.awt.RenderingHints java.awt.RenderingHints}. Any other value will throw
   * <code>IllegalArgumentException</code>. {@link java.awt.RenderingHints#VALUE_TEXT_ANTIALIAS_DEFAULT
   * VALUE_TEXT_ANTIALIAS_DEFAULT} may be specified, in which case the mode used is implementation
   * dependent.
   * @param fmHint - one of the text fractional rendering hint values defined in {@link
   * java.awt.RenderingHints java.awt.RenderingHints}. {@link java.awt.RenderingHints#VALUE_FRACTIONALMETRICS_DEFAULT
   * VALUE_FRACTIONALMETRICS_DEFAULT} may be specified, in which case the mode used is
   * implementation dependent. Any other value will throw <code>IllegalArgumentException</code>
   * @throws IllegalArgumentException if the hints are not one of the legal values.
   * @since 1.6
   */
  public FontRenderContext(AffineTransform tx, Object aaHint, Object fmHint) {
    if (tx != null && !tx.isIdentity()) {
      this.tx = new AffineTransform(tx);
    }
    try {
      if (KEY_TEXT_ANTIALIASING.isCompatibleValue(aaHint)) {
        aaHintValue = aaHint;
      } else {
        throw new IllegalArgumentException("AA hint:" + aaHint);
      }
    } catch (Exception e) {
      throw new IllegalArgumentException("AA hint:" + aaHint);
    }
    try {
      if (KEY_FRACTIONALMETRICS.isCompatibleValue(fmHint)) {
        fmHintValue = fmHint;
      } else {
        throw new IllegalArgumentException("FM hint:" + fmHint);
      }
    } catch (Exception e) {
      throw new IllegalArgumentException("FM hint:" + fmHint);
    }
  }

  /**
   * Indicates whether or not this <code>FontRenderContext</code> object
   * measures text in a transformed render context.
   *
   * @return <code>true</code> if this <code>FontRenderContext</code> object has a non-identity
   * AffineTransform attribute. <code>false</code> otherwise.
   * @see java.awt.font.FontRenderContext#getTransform
   * @since 1.6
   */
  public boolean isTransformed() {
    if (!defaulting) {
      return tx != null;
    } else {
      return !getTransform().isIdentity();
    }
  }

  /**
   * Returns the integer type of the affine transform for this
   * <code>FontRenderContext</code> as specified by
   * {@link java.awt.geom.AffineTransform#getType()}
   *
   * @return the type of the transform.
   * @see AffineTransform
   * @since 1.6
   */
  public int getTransformType() {
    if (!defaulting) {
      if (tx == null) {
        return AffineTransform.TYPE_IDENTITY;
      } else {
        return tx.getType();
      }
    } else {
      return getTransform().getType();
    }
  }

  /**
   * Gets the transform that is used to scale typographical points
   * to pixels in this <code>FontRenderContext</code>.
   *
   * @return the <code>AffineTransform</code> of this <code>FontRenderContext</code>.
   * @see AffineTransform
   */
  public AffineTransform getTransform() {
    return (tx == null) ? new AffineTransform() : new AffineTransform(tx);
  }

  /**
   * Returns a boolean which indicates whether or not some form of
   * antialiasing is specified by this <code>FontRenderContext</code>.
   * Call {@link #getAntiAliasingHint() getAntiAliasingHint()}
   * for the specific rendering hint value.
   *
   * @return <code>true</code>, if text is anti-aliased in this <code>FontRenderContext</code>;
   * <code>false</code> otherwise.
   * @see java.awt.RenderingHints#KEY_TEXT_ANTIALIASING
   * @see #FontRenderContext(AffineTransform, boolean, boolean)
   * @see #FontRenderContext(AffineTransform, Object, Object)
   */
  public boolean isAntiAliased() {
    return !(aaHintValue == VALUE_TEXT_ANTIALIAS_OFF ||
        aaHintValue == VALUE_TEXT_ANTIALIAS_DEFAULT);
  }

  /**
   * Returns a boolean which whether text fractional metrics mode
   * is used in this <code>FontRenderContext</code>.
   * Call {@link #getFractionalMetricsHint() getFractionalMetricsHint()}
   * to obtain the corresponding rendering hint value.
   *
   * @return <code>true</code>, if layout should be performed with fractional metrics;
   * <code>false</code> otherwise. in this <code>FontRenderContext</code>.
   * @see java.awt.RenderingHints#KEY_FRACTIONALMETRICS
   * @see #FontRenderContext(AffineTransform, boolean, boolean)
   * @see #FontRenderContext(AffineTransform, Object, Object)
   */
  public boolean usesFractionalMetrics() {
    return !(fmHintValue == VALUE_FRACTIONALMETRICS_OFF ||
        fmHintValue == VALUE_FRACTIONALMETRICS_DEFAULT);
  }

  /**
   * Return the text anti-aliasing rendering mode hint used in this
   * <code>FontRenderContext</code>.
   * This will be one of the text antialiasing rendering hint values
   * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
   *
   * @return text anti-aliasing rendering mode hint used in this <code>FontRenderContext</code>.
   * @since 1.6
   */
  public Object getAntiAliasingHint() {
    if (defaulting) {
      if (isAntiAliased()) {
        return VALUE_TEXT_ANTIALIAS_ON;
      } else {
        return VALUE_TEXT_ANTIALIAS_OFF;
      }
    }
    return aaHintValue;
  }

  /**
   * Return the text fractional metrics rendering mode hint used in this
   * <code>FontRenderContext</code>.
   * This will be one of the text fractional metrics rendering hint values
   * defined in {@link java.awt.RenderingHints java.awt.RenderingHints}.
   *
   * @return the text fractional metrics rendering mode hint used in this
   * <code>FontRenderContext</code>.
   * @since 1.6
   */
  public Object getFractionalMetricsHint() {
    if (defaulting) {
      if (usesFractionalMetrics()) {
        return VALUE_FRACTIONALMETRICS_ON;
      } else {
        return VALUE_FRACTIONALMETRICS_OFF;
      }
    }
    return fmHintValue;
  }

  /**
   * Return true if obj is an instance of FontRenderContext and has the same
   * transform, antialiasing, and fractional metrics values as this.
   *
   * @param obj the object to test for equality
   * @return <code>true</code> if the specified object is equal to this <code>FontRenderContext</code>;
   * <code>false</code> otherwise.
   */
  public boolean equals(Object obj) {
    try {
      return equals((FontRenderContext) obj);
    } catch (ClassCastException e) {
      return false;
    }
  }

  /**
   * Return true if rhs has the same transform, antialiasing,
   * and fractional metrics values as this.
   *
   * @param rhs the <code>FontRenderContext</code> to test for equality
   * @return <code>true</code> if <code>rhs</code> is equal to this <code>FontRenderContext</code>;
   * <code>false</code> otherwise.
   * @since 1.4
   */
  public boolean equals(FontRenderContext rhs) {
    if (this == rhs) {
      return true;
    }
    if (rhs == null) {
      return false;
    }

        /* if neither instance is a subclass, reference values directly. */
    if (!rhs.defaulting && !defaulting) {
      if (rhs.aaHintValue == aaHintValue &&
          rhs.fmHintValue == fmHintValue) {

        return tx == null ? rhs.tx == null : tx.equals(rhs.tx);
      }
      return false;
    } else {
      return
          rhs.getAntiAliasingHint() == getAntiAliasingHint() &&
              rhs.getFractionalMetricsHint() == getFractionalMetricsHint() &&
              rhs.getTransform().equals(getTransform());
    }
  }

  /**
   * Return a hashcode for this FontRenderContext.
   */
  public int hashCode() {
    int hash = tx == null ? 0 : tx.hashCode();
        /* SunHints value objects have identity hashcode, so we can rely on
         * this to ensure that two equal FRC's have the same hashcode.
         */
    if (defaulting) {
      hash += getAntiAliasingHint().hashCode();
      hash += getFractionalMetricsHint().hashCode();
    } else {
      hash += aaHintValue.hashCode();
      hash += fmHintValue.hashCode();
    }
    return hash;
  }
}
